1. Field of the Invention
The invention relates to a level comprised of a level body that is made of a hollow profiled section and has a bottom wall whose underside forms a measuring surface. The level body further has a top wall and sidewalls connecting the bottom wall and the top wall. The level further comprises a horizontal vial for carrying out a horizontal measurement. The vial is arranged within a window opening of the level body and is mounted in the level body by means of a securing device. The securing device secures a vial holder that holds the horizontal vial and has at least one clamping part that is movable relative to the vial holder for clamping the securing device within the level body.
2. Description of the Related Art
A level of the aforementioned kind is disclosed in German patent 36 06 774 C2. The vial holder has spreading cams that cooperate with spreading bodies that form clamping parts. By moving the spreading bodies, starting from a passive position, into their active position, the spreading cams are forced against the inner sides of the sidewalls of the level body so that the securing device for the horizontal vial is clamped within the level body. The device according to German patent 36 06 774 C2 provides for a simple assembly of the securing device for the horizontal vial within the level body, but it was found that upon temperature fluctuations the adjustment of the vial relative to the measuring surface of the level body can not be optimally maintained. Also, tolerances of the profile cross-section of the level body and of the parts of the securing device can be compensated only to a limited extent.
In addition, securing devices for horizontal vials are known that are glued into the level body or are snapped into place into a recess within the level body. In these devices there is also the problem that the measuring precision is affected by temperature fluctuations.
Moreover, a securing device is known with which the vial holder inserted into the window opening is pressed by means of a clamping part that is adjustable by a clamping screw against the inner side of the top wall of the hollow profiled section. The adjustment of the vial relative to the level body is realized in this connection by a minimal plastic deformation in the sense of depressing the top wall of the level body in an area in which the vial holder is pressed against the top wall. The temperature behavior of this securing device relative to the afore described securing devices is improved, but the assembly and adjustment are relatively complex. Also,. subsequent deformations of the top wall (for example, by impacts during the course of use of the level) have a direct effect on the adjustment of the horizontal vial relative to the measuring surface.